The underlying hypothesis of our clinical studies is that lowering or normalizing the high serum enzymes in Duchenne's muscular dystrophy (DMD) will be therapeutically useful. The high serum enzymes in twelve boys with DMD have been lowered using diethylstilbestrol (DES). The long range effects on muscle strength of chronic DES treatment are under study. We are attempting to clarify the mechanism by which DES lowers the serum enzymes. This may give a more precise insight into the cellular defect in DMD, responsible for muscle enzyme leakage in this disease. DES has been found to reduce the efflux from isolated mouse gastrocnemius muscle; and to localize intrasarcoplasmically. We are attempting to identify the exact nature of the radiolabelled compound which accumulates in muscle, and to determine where in the cytoplasm it localizes. Other studies have been directed to identifying characteristic features in the tissue culture of dystrophic muscle that may give a clue as to the site of the primary abnormality. One feature is the intracytoplasmic accumulation of crystalline materials in dystrophic myoblasts. We can now produce these crystals, and will attempt to identify them using crystallographic means. In addition, we have isolated wth the micromanipulator, single cells which remain viable for up to 10 days without proliferating. Attempts will be made to define a medium to permit cellular proliferation and cloning. Cloned myoblasts will be used to characterize DMD cells biochemically and by growth pattern, and compare with normal cells, similarly cloned. BIBLIOGRAPHIC REFERENCES: Morgan, J. and Cohen, L.: Use of papain in the preparation of adult mammalian skeletal muscle for tissue culture. In Vitro 10: 188-195, 1974. (appeared in print in April, 1975). Pacold, I., Morgan, J. and Cohen, L.: Absence of differences in platelet dihydroxyphenylalanine (DOPA) oxidase polymorphism in health and Duchenne's muscular dystrophy. Clin. Gen. 7: 435-441, 1975.